Studies of prostaglandin excretion in patients with various types of hypertension before and during treatment. Studies of prostaglandin excretion in patients and normals in whom the renin-angiotensin system is either stimulated or inhibited by either physiologic or pharmacologic means. Study of the effects of Indomethacin in patients with Bartter's syndrome. Study of the interrelationships between the prostaglandins, the kallikrein-kinin system and the renin-angiotensin system.